Ground-faults can occur almost anywhere. Anytime a conductor is inserted between a hot wire or a neutral wire and the ground, a ground-fault can occur. A common cause of ground-faults is worn insulation on conductors with exposed wires, making them susceptible to finding a path to ground. Another common cause of ground-faults is loose or bad connections in electrical devices. In many cases, a ground fault does not result in a tripped circuit breaker or blown fuse, but exists undetected.
Various kinds of ground-fault interrupters are available. Ground-fault interrupters are designed to break the electrical circuit when a ground-fault is detected. A ground-fault interrupter measures the magnitude difference in current between the hot and neutral wires. In a normal operating situation, the ground-fault interrupter should be measuring zero difference.
U.S. Pat. No. 6,246,556 issued Jun. 12, 2001 describes an electrical fault detection system. This system detects ground-faults in a circuit being monitored. A ground-fault sensor is responsive to current flowing through hot and neutral sides of a circuit by producing an output signal to a ground-fault detector circuit.
Known ground-fault interrupters and monitoring devices are typically designed for use with a single circuit and are relatively expensive such that in residential application the use of ground fault interrupters are often limited to higher risk areas such as bathrooms. Thus, there is a need for a cost efficient and reliable ground fault monitoring system and method.